Assuming the government defs doesn't care and wont cooperate with lawsuits.

Yes and no. Knowing your IP is sort of like knowing a PO box you rent. It can be used to try and transmit stuff to you, it can also be crudely geolocated, or if the person you're buying it from gives you up it can be traced directly to you as a person.

If someone wanted to, and you had terrible safety practices (such as opening mail you aren't expecting, the digital equivalent would be having software listening to ports) they could send you something harmful but this is probably not very likely unless you are pissing powerful people off (e.g. you're using that IP to distribute anti mossad documentaries or something :P). Your biggest threat is that somebody finds out who you are by going to your ISP and making them give you up.

If you are confident that this is very high effort and you are a small fish it's not much of a risk.